Azo dye developing agents having a group capable of forming a metal complex are described in, for example, U.S. Pat. Nos. 3,081,167, 3,196,014, 3,299,041, 3,453,107 and 3,563,739.
However, since the developing component of such azo dye developing agent has a reactivity, it sometimes occurs that the developing component does not develop a silver halide which it associated with the azo dye developing agent and which should be developed thereby, but develops a silver halide in another emulsion layer which must not be developed by the developing component. This results in an undesirable multilayer effect (inter image effect). Accordingly, it is preferred that a dye not having such developing component being reactive to silver halide is transferred onto an image-receiving layer.
Furthermore, a dye image-forming compound releasing an azo dye showing excellent light resistance by forming a chelate in a metal ion-containing image-receiving layer with the dye imagewise transferred therein from a light-sensitive element is preferred.
Dye image-forming compounds having such a property are described in U.S. Pat. Nos. 4,142,891, 4,147,544, 4,149,641, 4,148,642, 4,148,643, etc.
However, in these conventional compounds the chelating speed of the released diffusible dye is insufficient and hence the discovery of dyes showing a high chelating speed has been desired.
That is, if such a dye is discovered, a photographer can view more rapidly the transferred color image having normal colors (i.e., good color reproducibility) in instant photography, thus increasing the desirability of instant photography. Also, in addition to the improvement of the chelating speed of the diffusible dye, it has been desired that the dye does not reduce the following factors as compared to conventional compounds.
(1) The chelated dye has a good absorption when the dye forms a color image.
(2) The chelated dye has a large molecular absorption coefficient.
(3) The chelated dye is sufficiently stable to light.